HAPL June 20-21, Overview of Chamber/Blanket Work Presented by A.R. Raffray UCSD With contributions from CTC Group and MWG Blanket contributions: M. Sawan, I. Sviatoslavsky, X. Wang HAPL Program Workshop Livermore June 20-21, 2005

HAPL June 20-21, Outline Revisit different blanket options for large chamber Assessment and selection for more detailed study Agree on two HAPL cases (baseline and advanced) as a basis for focusing our design and integration study (CTC + MWG) Invited presentation on IFE chamber effort at ISFNT-7 in Tokyo last month, to be published in Fusion Engineering & Design: “Progress Towards Realization of a Laser IFE Solid Wall Chamber”

HAPL June 20-21, Set Chamber Size Based W Armor Survival Constraints Assume no chamber gas Assume preliminary constraint of 2400°C on W based on initial RHEPP roughening threshold results (~1.2 J/cm 2 ) -constraint to be revisited as data become available (conference call, side meeting to discuss this) Example chamber parameters -Yield = 350 MJ -R = 10.5 m (large chamber) -Rep. rate ~ 5 for 1750 MW fusion (could be higher) Required P Xe as a Function of Yield to Maintain T W,max <2400°C for 1800 MW Fusion Power and Different R chamber

HAPL June 20-21, Blanket Scoping Study: Recent Focus Revisit options for large chamber (R= 10 – 11 m) with the goal of converging on: 1.A baseline case with minimum risk in getting there based on present day material development and knowledge (in particular regarding the use of low-activation ferritic steel and associated temperature limit). 2.An advanced case (with ODS-FS with higher development risk and probably higher cost also) as an indication of what could be gained with a more ambitious material R&D program. Three blanket options 1.Self-cooled Li 2.Other self-cooled liquid breeder: Pb-17Li (reduced loads in large chamber amenable to self-cooled option instead of dual coolant or He- cooled) (flibe not included since our previous concerns still stand: high MP, small temperature window, need ODS FS, little current worldwide effort, scale and risk of R&D effort) 3.He-cooled ceramic breeder

HAPL June 20-21, Self-Cooled Li Blanket for Large Chamber Large chamber size leads to the division of blanket modules in two (upper and lower halves) Details to be presented by I. Sviatoslavsky and M. Sawan The design is based on an annular geometry with a first Li pass cooling the walls of the box and a slow second pass flowing back through the large inner channel.

HAPL June 20-21, Thermal Insulation Between Li and FS Wall Required to Minimize Heat Flow From High Temperature Li in Inner Channel to Lower Temperature Li in Annular Channel Sandwich insulator considered. This could be something like porous SiC between two thin FS walls. No final design yet but it is assumed that this can be readily developed since the insulator is not exposed to lithium. Inner Channel Li Annular Channel Li Sandwich insulator: FS-SiC-FS

HAPL June 20-21, Large Chamber Results in Lower Heat Loads: --> Less Demand on Blanket Design

HAPL June 20-21, Re-assess Possibility of 2 Brayton Cycle Configurations in Combination with Lower Heat Load Blanket + Intermediate HX -  T HX ~ 50°C -  comp =  turb = Effect. recup = 0.95 I.3 Compressor stages (with 2 intercoolers) + 1 turbine stage;  P/P~0.05; 1.5 < r p < 3.5 II.4 Comp. stages (+ 3 intercoolers) & 4 turb. stages (+ 3 reheats);  P/P~0.07 ; 1.5 < r p < 3.5 Higher performance (but more complex)

HAPL June 20-21, Changing from Brayton I to Brayton II Does Help but Major Effect is Changing from RAFS (T max <550°C) to High Temperature ODS FS (<700°C) 2. Efficiency Not Much Affected by Rep Rate; Should Operate at Maximum Possible Rep Rate on This Basis

HAPL June 20-21, Pumping Power Increases with Rep Rate, Reflecting the Higher Flow Rates Required for Increasing Fusion Power Pumping power requirements much higher for Brayton II than Brayton I Overall, pumping power values seem reasonable

HAPL June 20-21, Example Effect of Rep Rate on Various Blanket Parameters for Example Case with Brayton I and RAFS (e.g. F82-H) Maximum Li/FS interface temperature < 560 °C

HAPL June 20-21, Re-assess Possibility of Ceramic Breeder Blanket in Combination with Brayton Cycle II (Brayton I yields too low efficiency) and Example Rankine Cycle for Larger Chamber Example Rankine Cycle with superheat, single reheat and regeneration (not optimized): -Turbine isentropic efficiency = 0.9 -Compressor isentroefficiency = 0.8 -Min. (T cool –T steam, cycle ) > 10°C -P min = 0.15 bar -  T HX ~ 50°C -  comp =  turb = Effect. recup = 0.95 CB + Be Blanket Module

HAPL June 20-21, Ceramic Breeder Blanket Performance Brayton cycle II requires a rather high pumping power Rankine cycle more attractive, but this would require a stronger module (more structure/complex design) to accommodate high pressure in case of accident (module + steam generator) and to avoid Be/steam reaction.

HAPL June 20-21, Blanket Parameters for Example Cases Yield = 350 MJ; R chamber =10.5 m; Rep rate = 5; P fusion =1750 MW -Self-cooled concepts more attractive than CB -Currently: T Li/FS,allow < °C T PbLi/FS,allow < 450 °C (but old data and questionable extrapolation, new experiments needed) -In terms of performance w/o an outer insulation layer, it is most likely that Li will be superior -Based on performance and weight (designing for Pb-17Li more challenging, requiring more structure), we propose the self-cooled Li blanket as the front runner choice and keep Pb-17Li as back up.

HAPL June 20-21, Recommended Self-Cooled Li Blanket Cases ( with input from and agreement of CTC and MWG members) Baseline Case: FS max. avg. temp. through its thickness < 525°C; (Regular LAF)FS max. temp. in FW < 550°C FS/Li max. interface temp. in blanket < 560°C FS/Li max. interface temp. outside blanket < 575°C (with the assumption that no protective layer is needed) Advanced Case: FS max. avg. temp. through its thickness < 700°C; (ODS-FS)FS max. temp. in FW< 720°C FS/Li max. interface temp. in blanket < 775°C (Will need protective layer or coating, e.g. W) FS/Li max. interface temp. outside blanket < 800°C (Will need protective layer or coating, e.g. W)

HAPL June 20-21, Typical Parameters for the Proposed Cases A rep rate of 5 used in this example Since the cycle efficiency does not change and the pumping power penalty is reasonable, it would be advantageous to operate at higher rep rate if allowed by other considerations

HAPL June 20-21, Next Step Ready to proceed to more detailed and integrated design for our base case -More detailed blanket and in-reactor component design and layout -System -Safety